Cellular communications systems are becoming ever more common. In cellular systems, a communications area is divided into a plurality of cells. Each cell normally includes at least one base station. The base station in each cell communicates with a plurality of devices, e.g., mobile terminals, located within the same cell as the base station. The base station usually serves as a mobile terminal's point of attachment to a communications network which includes the base station. Since access to the communications network is obtained by a mobile terminal through the base station to which it is coupled, e.g., by a wireless link, base stations are sometimes known as access nodes.
In cellular wireless data communication systems, data is often transported between a base station and a mobile terminal via a quantum of resource called a traffic segment. In such systems, the available resource for data communication in a cell, e.g., a traffic channel, is often partitioned into multiple traffic segments. Control information may be transmitted via other channels, e.g., acknowledgment channels. Downlink traffic segments transport data traffic from a base station to one or more wireless terminals, while uplink traffic segments transport data traffic from one or more wireless terminals to a base station.
Acknowledgment channels include acknowledgment segments which can be used to indicate whether or not information in one or more corresponding traffic segments was successfully received. An uplink acknowledgment channel can be used by a mobile device to signal that information transmitted by the base station was successfully received, e.g., was able to be decoded by the mobile terminal. This may be achieved by sending an Acknowledgement (Ack) in a segment of the uplink acknowledgment channel. Failure to successfully receive information may be communicated by sending a negative acknowledgement (NAK) instead of an ACK. The ACK and NAK can be represented using a single bit, e.g., a 1 to represent an ACK and a 0 to represent a NAK. A downlink acknowledgment channel can be used by a base station to signal whether or not information transmitted by the mobile in an uplink traffic channel was successfully received, e.g., was able to be decoded by, the base station in the same manner that the uplink acknowledgement channel is used by the mobile terminals. The transmitter, e.g. base station or mobile terminal, upon receiving a NAK can choose to retransmit the same data.
The retransmission of the previously transmitted information represents the transmission of redundant information. While retransmission can lead to improved transmission success, it can be a relatively costly process since transmission resources are consumed by the need to transmit the same data multiple times. The selective retransmission process can also lead to delays in achieving a successful transmission result.
The mechanism by which a determination is made as to whether or not redundant information, e.g., previously transmitted information, needs to be transmitted is sometimes called an automatic repeat request (ARQ) mechanism.
In order to increase error resiliency and reduce the need for the retransmission of data, error correction coding may be used. Error correction codes (ECCs) result in the addition of redundant information, e.g., one or more ECCs, being added in a selective manner to the transmitted information. By using the redundant information, it may be possible to recover transmitted information even when some errors occur during the transmission process.
In order to provide efficient utilization of communication bandwidth, it is generally desirable to minimize the amount of redundant information, e.g., error correction codes, transmitted along with the information to be communicated. As a result, even when error correction coding techniques are used, as a result of transmission errors, there may still remain a need for an ARQ mechanism.
In view of the above discussion, it should be appreciated that improved ARQ mechanisms and methods of communicating redundant information to increase the efficient utilization of limited amounts of bandwidth available to communicate data are both needed and desired.